The storage market posted its strongest growth in years in the fourth quarter of 2005, with external storage system sales growing 17.9% from the same quarter in 2004, according to IDC.

"The external disk storage systems market growth continued to accelerate through the year," said Brad Nisbet, IDC's program manager for storage systems. "Data growth was one driver, but the availability of affordable systems that support multiple tiers of storage to address data protection, business continuity requirements, and online, active archives also contributed."

EMC maintained its lead in the external disk storage systems market with 20.6% revenue share, followed by HP and IBM with 18% and 15.9%, respectively. That said, both EMC and HP grew at a slower pace than the rest of the market, both for the quarter and all of 2005 (see tables below). Dell and Hitachi rounded out the top five with 9.2% and 7.3% share, respectively. Among the top five, Dell and IBM posted the strongest year-over-year revenue growth during the fourth quarter, with 54.2% and 46.8% growth, respectively.

The total network disk storage market (NAS combined with open and iSCSISAN) grew 24.2% to more than $3.1 billion. EMC continued to lead the total network storage market with 26.9% revenue share, followed by HP and IBM with 19.7% and 13.6%, respectively. Dell and IBM posted the strongest year-over-year revenue growth for the quarter, with 64.6% and 54.9% growth. IDC noted that IBM's strong year-over-year growth was due in part to an easy comparison with an unusually weak fourth quarter of 2004, but nonetheless, Big Blue achieved its highest quarterly revenue in four years.

In the NAS market, which grew 23.3% year over year, EMC led with 39.5% revenue share, followed by NetApp with 31.8% share. NetApp has claimed that it would lead in NAS sales without the inclusion of content-addressed storage (CAS).

The iSCSI SAN market continues to be red-hot, with 130% growth to $94 million. NetApp continues to lead the iSCSI market with a 26.2% share, followed by EMC with 20.6%.

Natalya Yezhkova, IDC Storage Systems senior research analyst, said the "sweet spot" for the storage market last year was systems priced between $50,000 and $150,000. "This segment, which serves the needs of a broad range of data centers and applications, grew to over $1 billion in the fourth quarter," Yezhkova said.

For the full year, EMC maintained its lead in the external disk storage systems market with a 20.7% revenue share, followed by HP and IBM with 18.3% and 13.6%, respectively. Dell and Hitachi rounded out the top five with 8.4% and 8.0%. Dell and IBM posted the strongest year-over-year sales growth during 2005, at 36.5% and 23.8%.

For the full year, the total disk storage systems market grew 10.7% to $23.7 billion. In the total worldwide disk storage systems market, HP led with a 23.1% share, followed by IBM with 20.3% and EMC with 14.2%.